Cryostat and Thermal Insulation
The cryostat is the vacuum-insulated enclosure that keeps room-temperature heat from reaching the cold magnet.
A thermos around the magnet
The cryostat is the vacuum vessel that surrounds the cold mass and isolates it thermally from the room-temperature world. Heat reaches a cold magnet by conduction, convection, and radiation; the cryostat attacks all three with high vacuum, multilayer insulation, and intermediate temperature shields. Every watt it blocks is a watt the refrigeration plant does not have to remove.
Three heat paths, three defenses
- Convection: eliminated by the insulating vacuum.
- Radiation: reduced by multilayer insulation and thermal shields.
- Conduction: minimized through supports and current leads.
- Penetrations: each is a designed thermal-leak path to manage.
Supports are a thermal compromise
The cold mass must be held rigidly against large electromagnetic forces, but every mechanical support is also a conduction path for heat. Support design trades structural stiffness against thermal leak, using long, low-conductivity load paths and intermediate temperature interception. It is a recurring theme in cryogenics: structure and heat leak are the same components.
Why it matters for the breeder
A good cryostat shrinks the refrigeration load, which shrinks the plant and the power it draws. Combined with the shield's nuclear-heating limit, the cryostat's performance sets how much thermal margin the magnet has. It is a quiet enabler of the high-field design rather than an afterthought.
Vacuum integrity over life
The insulating vacuum must hold across the machine's life despite thermal cycling and any outgassing from irradiated materials, because a degraded vacuum sharply raises the heat leak. The cryostat is therefore designed for maintainable pumping and leak detection, treating vacuum integrity as an operating requirement rather than a one-time commissioning check.
This page documents a design and simulation study, not a built machine. Construction begins Q2 2027; first-of-a-kind first tritium is targeted near 2030. Figures are computed, reproducible targets, not measurements.